# Edge Clusters & CDN Layer (Provider Clustering)

Group nearby provider nodes into clusters (Edge PoPs) to:

* Reduce RTT and egress costs for popular destinations.
* Support content distribution (web, media, API, game patches).
* Add resilience and horizontal scaling for high-demand locales.

**Cluster Formation & Membership**

* Eligibility: Rep\_i above threshold, stake ≥ minStake\_cluster, region/ASN match.
* Membership protocol: SWIM-style gossip (failure detection + membership) over QUIC control channel.
* Shard & routing: Consistent hashing (e.g., rendezvous hashing) on content key {host, path, cache-key}.
* Leader/Coordinator: RAFT-lite or epochal leader via VRF lottery (prevents sticky leaders).
* Service ads: Cluster publishes SRV records to Intelligent DNS with health and capacity

**CDN Data Plane**

* Cache tiers: L1 (RAM) on edge providers; L2 (NVMe) within cluster; optional L3 regional.
* QUIC Anycast: announce shared VIP via anycast/GeoDNS; ECMP within cluster using 5-tuple hash.
* Content addressing: origin fetch over QUIC; cache key = normalized URL + Vary headers + E2E policy.
* Integrity: optional content signatures (origin-signed SHA-256) or Merkle chunk trees for multi-source fetch.<br>

**Control Plane & Cache Coordination**

* Directory service: gossip index of hot keys, frequency counts, and TTLs.
* Prefetch: predictive fetch based on demand spikes (short-term EWMA, Holt-Winters).
* Admission & eviction: ARC/LIRS with priority boost by Rep\_i and regional hit ratio.
* SLA policy: content owners may publish cache directives via signed manifests.

**Security & Privacy**

No payload inspection for private traffic. CDN applies only to opt-in content (public assets or owner-signed).<br>

* Encrypted transport: QUIC/TLS; optional object-level AEAD for CDN objects at rest.
* Abuse control: per-AS/region rate caps; anomaly detection (synchronicity, cache-miss storms).

**Cluster Incentives & Revenue Split**

* Route fees: per-hop share (already defined) for relay work.
* CDN fees: request- and byte-priced; split by work share (serves, hit ratio, egress saved) and Rep\_i multiplier.
* Treasury: portion reserved for cold-start replication and cross-region seeding.

**Cluster Selection & Anycast Flow**

<figure><img src="/files/xkACygA8AViAV2wTyWg7" alt=""><figcaption></figcaption></figure>

**Cluster score for DNS**

`Sel_cluster = H( median(Rep_members), hit_ratio, avg_RTT, egress_savings, price )`

where H is a normalized harmonic mean to avoid a single weak dimension dominating.

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